Tiled walls have long been popular, particularly for bathrooms, kitchens and the like. In spite of the popularity of tiled walls, these walls present certain problems. First, the grout may become a breeding place for stain producing mildew. Once stained the grout is extremely difficult to clean since it is porous and the stain may permeate through the grout. Secondly, the grout may loosen and fall out of the spaces between the tiles. Once the grout is cracked moisture may seep in behind the tiles and loosen them from the supporting wall. In addition, tile is difficult to install in perfectly straight lines. Also, tile is relatively expensive and time consuming to install compared to other walls.
Wall boards or tile boards simulating tiles embedded in grout, such as the one disclosed in application Ser. No. 123,487 filed Nov. 20, 1987, incorporated herein by reference, remedy these problems associated with tiled walls. Such wall boards are finding increased acceptance and usage. These wall boards typically are provided in large sections or panels, e.g. about four feet wide and about four feet high, about four feet wide by eight feet high, etc. When a large area, such as a large wall, is to be covered generally two or more wall board sections or panels are needed. These individual wall board panels are joined in a side-by-side or stacked arrangement, usually in a tile-to-tile arrangement. This joining of the individual wall board panels results in an unsightly seam between adjacent wall board sections. This seam can be eliminated by leaving a space between the adjoining wall board panels and filling this space with grout or caulking material to produce a grout line between the panels. This procedure, however, is time consuming and requires additional effort to insure that the grout or caulking material is worked so as to have a concave surface in order to conform to the simulated grout lines in the wall board panels.
By the use of the extension joint of the instant invention a simulated grout line is created between adjoining wall board panels thereby providing an aesthetically appealing seamless appearance without the necessity of caulking or grouting between adjacent wall board panels.